The present invention relates to a control apparatus of an electric vehicle provided with an electric motor and a transmission transmitting a power of the electric motor to a wheel side output shaft.
There has been known a hybrid vehicle which distributes a power of an internal combustion engine to a wheel side output shaft and a power generator, and transmits a power of an electric motor to the wheel side output shaft via a transmission (refer to Japanese Laid-Open Patent Publication No. 2004-203219).
In the hybrid vehicle described in Japanese Laid-Open Patent Publication No. 2004-203219, the structure is made such that a torque transmitted to the wheel side output shaft from the electric motor is increased and decreased by switching engagement and disengagement of a plurality of friction type engagement mechanisms provided in the transmission so as to change gear. Further, in the control apparatus described in the publication, in order to suppress a shift shock at a time of shifting gear, there is executed a rotation synchronization control synchronizing a rotation speed of the electric motor prior to the gear shift toward a rotation speed after the gear shift, at a time of gear shift of the transmission. For example, in the case that the gear is shifted to another gear of a higher reduction ratio, the rotation speed is adjusted in such a manner that the rotation speed of the electric motor becomes higher little by little in a shifting process of the gear. In the case that the gear is shifted to another gear of a lower reduction ratio, the rotation speed is adjusted in such a manner that the rotation speed of the electric motor becomes lower little by little in the shifting process of the gear.
In this case, in the hybrid vehicle, in the case that a shift lever or the like is operated by a driver, and it is detected that the operated position is a neutral position, the excitation of the power generator and the electric motor is shut off and the power generator and the electric motor are set in an idle running state, whereby there is generated a neutral state in which the power transmission to the wheel side output shaft is shut off.
In this case, if a neutral request for shutting off the power transmission to the wheel side output shaft as mentioned above is outputted during the execution of the rotation synchronization control, there is executed the neutral control of shutting off the application of current to the power generator and the electric motor on the basis of the request. If the neutral control is executed during the execution of the rotation synchronization control as mentioned above, the adjustment of the rotation speed of the electric motor through the rotation synchronization control is interrupted. Thus, there is a risk that a shift shock is generated from the transmission in some state of the engagement mechanism.
There is a risk that the shift shock as mentioned above is generated not only in the hybrid vehicle provided with the internal combustion engine and the electric motor, but also in an electric vehicle having a power source constituted only by an electric motor and transmitting the power to the wheel side output shaft via a transmission in the same manner.